The Issaquah Alps is the unofficial name for the

highland Highlands or uplands are areas of high elevation such as a mountainous region, elevated mountainous plateau or high hills. Generally, ''upland'' refers to a range of hills, typically from up to , while ''highland'' is usually reserved for range ...

s near

Issaquah, Washington Issaquah ( ) is a city in King County, Washington, United States. The population was 40,051 at the 2020 census. Located in a valley and bisected by Interstate 90, the city is bordered by the Sammamish Plateau to the north and the " Issaquah ...

, a suburb of

Seattle Seattle ( ) is the most populous city in the U.S. state of Washington and in the Pacific Northwest region of North America. With a population of 780,995 in 2024, it is the 18th-most populous city in the United States. The city is the cou ...

, including

Cougar Mountain Cougar Mountain is a peak in the Issaquah Alps in King County, Washington. It is part of the highlands in the Eastside suburbs of Seattle, and at it is the lowest and westernmost of the Alps. About two-thirds of Cougar Mountain has experienc ...

, Squak Mountain, Tiger Mountain, Taylor Mountain, Rattlesnake Ridge, Rattlesnake Mountain, and Grand Ridge. The term was invented in 1977 by noted nature author

Harvey Manning Harvey Manning (July 16, 1925 in Ballard, Seattle, Washington - November 12, 2006 in Bellevue, Washington) was a noted author of hiking guides and climbing textbooks, and a tireless hiking advocate. Manning lived on Cougar Mountain, within the c ...

within the pages of his trail guidebook ''Footsore 1'', elevating their status from foothills to "Alps" to advocate preservation. Manning himself lived on a developed section of Cougar Mountain in his "200 meter hut". In 1979, Harvey Manning helped to found the Issaquah Alps Trails Club to care for the trails and to push for public ownership of the Alps. The IATC, which is headquartered in Issaquah (nicknamed "Trailhead City"), conducts frequent guided hikes throughout the Alps. The Issaquah Alps follow

Interstate 90 Interstate 90 (I-90) is an east–west transcontinental freeway and the longest Interstate Highway in the United States at . It begins in Seattle, Washington, and travels through the Pacific Northwest, Mountain states, Mountain West, Great Pla ...

from the shore of

Lake Washington Lake Washington () is a large freshwater lake adjacent to the city of Seattle, Washington, United States. It is the largest lake in King County, Washington, King County and the second largest natural lake in the state of Washington (state), Was ...

almost to the western face of the

Cascade Range The Cascade Range or Cascades is a major mountain range of western North America, extending from southern British Columbia through Washington (state), Washington and Oregon to Northern California. It includes both non-volcanic mountains, such as m ...

. The hills are composed of

andesitic Andesite () is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predomina ...

volcanic rock lying on top of older tightly folded rocks from the coastal plain of the North Cascade subcontinent that docked with Washington about 50 million years ago as the entire continent of

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

moved west across the ocean. The Alps were heavily eroded by

glacier A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires ...

s in the last

ice age An ice age is a long period of reduction in the temperature of Earth's surface and atmosphere, resulting in the presence or expansion of continental and polar ice sheets and alpine glaciers. Earth's climate alternates between ice ages, and g ...

. The Vashon lobe of the ice sculpted Rattlesnake Ledge, steeply carved the east and west sides of Squak Mountain, and deposited a large erratic on Cougar Mountain, Fantastic Erratic. Cedar Butte rises abruptly from the

moraine A moraine is any accumulation of unconsolidated debris (regolith and Rock (geology), rock), sometimes referred to as glacial till, that occurs in both currently and formerly glaciated regions, and that has been previously carried along by a gla ...

between Rattlesnake Ledge and the absolute front of the Cascades. It is sometimes considered part of the Issaquah Alps but it is a relatively young symmetrical volcanic cone and is therefore more closely related to neighboring Mount Washington to the east than the old weathered hills of the majority of the Alps.

Summits

elevation The elevation of a geographic location (geography), ''location'' is its height above or below a fixed reference point, most commonly a reference geoid, a mathematical model of the Earth's sea level as an equipotential gravitational equipotenti ...

* Squak Mountain, elevation * Taylor Mountain, elevation * Tiger Mountain ** Middle Tiger Mountain, elevation ** East Tiger Mountain, elevation ** South Tiger Mountain, elevation ** West Tiger #1, elevation ** West Tiger #2, elevation ** West Tiger #3, elevation * Rattlesnake Ridge ** Rattlesnake Ledge, elevation ** Rattlesnake Mountain (East Peak), elevation ** Rattlesnake Mountain (West Peak), elevation

References

* *

External links

Issaquah Alps Trails Club
*Trail reviews of hikes in the Issaquah Alps a
Hiking with my Brother
{{DEFAULTSORT:Issaquah Alps Cascade Range Mountain ranges of Washington (state) Landforms of King County, Washington